The best way to manage the number of Community Members in your library is by muting anyone who posts irrelevant content. Here’s how to do it:
Find an asset in your library shared by that Community Member and click to open the asset’s [...] menu.
Click Mute content from @communitymember.
We’ll automatically stop saving that Community Member’s content forever (or at least until you unmute them). We’ll also automatically delete any of their content that has been saved in the past, which removes them from your list of Community Members and frees up space for someone new.